Flow sensors as accessories of the respiratory mechanics modules or the anesthetic machines are the key devices that deliver the information on the airway communicating between the patients and the anesthetic machines to the monitoring modules, and play an important role in monitoring the respiratory mechanics parameters and the working states of the anesthetic machines. The monitoring of the respiratory mechanics parameters during operations not only determines the accuracy and safety of the respiratory mechanics modules in monitoring the patients' pulmonary ventilation process, but also plays a decisive role in the ventilation modes and the performance that the anesthetic machines can achieve.
Current commercially-available patient monitoring systems or anesthetic machines having respiratory mechanics parameters monitoring functions have not been provided with the function for monitoring the installation states of the flow sensors, nor do any technical solutions or relevant patents give clues thereto. The most frequently used method is to make the external diameter of the air nozzle located at the sensor module end into different sizes in order to prevent blind insertion, or to apply different indicative colors for guiding the user on correct installation of the flow sensors. Though this kind of method woks to some extent, it is not sufficient to prevent a user without any engineering knowledge from erroneous operations. Moreover, this kind of connection is not adapted for connecting the gas tubing of the flow sensors available on the market.
In another kind of respiratory mechanics module a trapezoidal socket and a photo-coupled circuit are provided at the back end of the flow sensor, which can discern the types of flow sensors and prevent the reverse connection of the flow sensors. This module provides timely and reliable solutions, but unfortunately is compromised by a relatively high cost. Moreover it can not address the problem as to the reverse connection of the flow sensors at the patient end either.